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Effect of New Accounting Pronouncements - Additional Information (Detail) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |
Corporate income tax rate | 21.00% | 21.00% | 35.00% |
Operating lease right of use assets | $ 368.8 |  |  | $ 379.6
Operating lease liabilities | 410.7 |  |  | 420.3
Net rent related asset and liabilities |  |  |  | 38.3
Cumulative effect of adoption of new accounting standards |  |  |  | 2.4
Reclassification from accumulated other comprehensive income, current period, before tax | 0.2 |  |  |
Accumulated Other Comprehensive Earnings (Loss) [Member] |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |
Cumulative effect of adoption of new accounting standards | $ (0.2) |  |  | $ (0.2)
Accounting Standards Update 2018-02 [Member] |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |
Cumulative effect on retained earnings |  | $ 6.6 |  |

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- Definition For a classified balance sheet, the cumulative difference between the rental income or payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense, by the lessor or lessee, respectively, more than one year after the balance sheet date. Such receivable is reduced by allowances attributable to, for instance, credit risk associated with a lessee. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.3(a)(4)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=77902458&loc=d3e39927-112707 + Details
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- Definition Present value of lessee's discounted obligation for lease payments from operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977 + Details
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